The present item is a product of the marked growth of interest in botany in general and the flora of Switzerland in particular exhibited during the Enlightenment, and exemplified by Jean-Jacques Rousseau's celebrated 'Lettres élémentaires sur la botanique'. Alexandra Cook's 'Jean-Jacques Rousseau and Botany' (2012) is a useful discussion of the subject (see in particular Chapter 3: 'Helvetia mediatrix: the atmosphere of eighteenth-century Swiss science'). It provides in addition a mass of invaluable observational evidence. 396pp, 8vo. The main text, on 186pp of greyish paper, is paginated; it is interleaved with paper of a lighter hue, with five supplemental pages at the rear. Two leaves of paper are tipped in: the first carries a two-page list headed 'Mentha.'; the second carries a one-page list headed 'Trifolium: Halleri'. Internally in good condition, on lightly aged paper; in worn half-binding with vellum spine and corners and grey paper boards, a blank white label cut into a pattern is on the front board, and on the spine a simple white label with '670' in manuscript. Some flowers are pressed between the pages describing the fifteenth class, Tetradynamia. The text is almost entirely written in the Latin language, with occasional observations in French and German. It is in a neat Latin hand, rather than German cursive handwriting. A painstaking and detailed presentation, giving a systematic arrangement and description of the plants of Switzerland, clearly the product of many years of field study, with the interleaved portions supplementing the information within the main text, and referencing the Swiss naturalists Albrecht von Halle (1708-1777) and Abraham Gagnebin (1707-1800). (A work similar in arrangement is the 'Flora Helvetica' of Johann Rudolf Suter (1766-1827), published in 1802.) There are no indications of the authorship or provenance of the volume, but the handwriting would appear to indicate that it dates from around the end of the Eighteenth Century. The main text gives a formal presentation divided into 21 classes from Monandria to Monoecia, these being the first 21 of the 24 classes within the Linnaean taxonomy. The orders within these classes are numbered from 1 to 492; and five supplementary pages at the rear contain orders numbered 122 to 160, under the headings 'umbellae simplices' and 'umbellae compositae'. The interleaved portion of the text gives observational information with reference to locations within Switzerland. Two examples convey the arrangement of the work. The first example is to be found within the fourth class, Tetrandria, where an entry within the main text reads: 'B. | flores incompleti. | 63. Alchemilla. Cal. 8 – fid. infer. Cor. Nulla. | [63.] 271. A. alpina. - H. 1567 – S. I. 96 – G. n. 366 – Dc. II. 589. | fol. subtus sericeis argenteis.' Facing this, in the interleaved portion, is: '271. in pascuis Turanis editioribus frequens, Chasseralle, Mitelbertg. Hall. jam. sed minor quam quae in Alpibus provenit.' The second example, including French text, is within the sixth class, Hexandria, with the entry in the main text reading: '198. Uvularia. Cor. 6 – petala, campanul. Petala basi intus nectarifera fovea. Filamenta antheris breviora. | 600. U. amplexifolia – H. 1237 – S. I. 196 – G. n. 771 –'. Facing this, in the interleaved portion, is: '600. Primus reperit Gagnebin, au fond de la Combe Biosse, versus Mont. Chasseral, à la Champ d'Abèl, aux Combes de Valanvron, et au Pouilleret dans les abîmes. Hall.' There are hundeds of other interleaved observations, such as 'ubique colitur in hortis, passim ex muris antiquis', 'in pascuis Turanis frequens insolita magnitudine et pulchretudine luxuriat in m. Chasseral.' and 'Biennae ad lacuni inter Passquart et Thielam.'